Off-road drivetrain issue.

[gw33gp]

I just spent a week on an off-road trip in Western Colorado and Eastern Utah. A issue came up that I have not experienced before. When going downhill in 4 WD low range and going around corners I would get this thump from the drivetrain with the truck slipping forward a little. It was almost like the like the transfer case chain was jumping a tooth. I installed a new chain in it last year so I doubt it is doing that. I also did a trip in the Maze Section of Canyonlands National Park last year after the transfer case work with no issues.

I am thinking it was from the transfer case binding up while going around the corner and suddenly releasing with a tire slipping. What I can't figure out is why it would not do it while going uphill around a corner. It could possibly be that the extra power used while going uphill would make the tires constantly slip to keep the binding to a minimum. I don't recall it doing it while on level ground either, only downhill. I am a little baffled because it has not done that before that I can remember.

I also thought the 33" tires could be contributing to it with the better traction, but I have been running them for many trips before without an issue. Normally, I would not be concerned about it but those thumps were more like bangs and seemed to be quite a shock to the drivetrain. So, I am throwing it out here to see if anyone has an idea why it suddenly popped up and things I could check out to diagnose it. I haven't had time to get under it yet, only a quick visual for anything that was very obvious.

 

[Uncle Gump]

I had mine do something this winter when I was in 4H playing in the snow a bit.

I come off the snow onto some pavement that had good traction. I turned into a parking lot which was a pretty tight turn... and I felt the driveline load up (think stuck brake caliper) and it released with a BANG! I could have sworn something broke. But I've put 25k on it since then and it all seems well and good.

I was thinking your headed downhill... weight on the front tires... turn a bit tight... front wheels had traction.... Bang!

I would think if something went wrong in the T-case... draining the fluid would tell you about it.

 

[sgtsandman]

Are you running a front locker? The drivetrain could be binding if you are and it’s engaged.

 

[gw33gp]

I know 4WD will bind the transfer case when turning while in 4WD. The binding is mild with low traction and much worse with good traction. I don't use 4WD on dry pavement for that reason. Off-road has never been an issue unless I am on solid rock. I am perplexed why it is suddenly doing this.

I don't have a front locker. I run Torsen differentials front and rear but I have been running both for a long time with no issues.

I suspect my drivetrain has gotten enough wear and slack that it tends to bang more when releasing the binding under certain conditions. I will get under it and do a more thorough inspection this weekend. Usually, I get more of a hopping action when the binding is released with good traction.

 

[85_Ranger4x4]

It could possibly be that the extra power used while going uphill would make the tires constantly slip to keep the binding to a minimum. I don't recall it doing it while on level ground either, only downhill.

Power and weight transfer would make the fronts slip easier going uphill.

Totally a shot in the dark but you might check over your front driveshaft too. The u-joint and I think you have a CV joint. Possibly the front axle shafts as well.

Your limited slip is tamer than a locker but it will wear on your front driveline more than if it was all stock.

 

[gw33gp]

The front drive shaft is fairly new. My CV joint got very worn when the grease boot disintegrated and slung out all the grease leaving little to no lube left to lubricate the CV joint. I found out it was easier to replace to whole front driveshaft rather than just the CV joint and it was not that much more money either.

I do plan to check out the entire drivetrain though, at least everything that does not require disassembly. I have a brother that is good professional mechanic that lives in Kansas. I am going to be there around the September/October time frame. If I can't find anything wrong with the drivetrain, I will have him look at it. If there is anything wrong, he will find it.

 

[gw33gp]

I know I am really late in revealing the cause of the problem, but in case someone sees this thread with a similar issue here is what I found. When I was in Kansas, we had the truck on a lift and my nephew went around checking things. He noted right inner tie rod was worn and had play in it. When I got home, I replaced both inner tie rods and never had that issue while off-road in 4WD again.

 

[4x4prepper]

In a perfect world your front and rear axles would have exactly the same ratio, using the same gear set, and same size, as an example both Dana 44s. But, even with say an 8.8 rear and front Dana 35, that supposedly had exactly the same ratio, and both turned exactly at 4.10 to 1, they are going to be slightly different in real life. Because the front carries more weight then the rear, the tires squish a bit flatter, then when you go downhill, you transfer even more weight to the front, then you turn which deforms the radial tire even more.

Sort of like having a tandem axle trailer, making a tight turn, and watching your rear inner start to fold the sidewall on truck/P rated tires.

Though if this was my truck, I would check the rear driveshaft at the axle. Even with blue loc-tite I have had the bolts loosen up on Rangers, B2, and Aerostars. Because of this, I keep a spare bolt in my glove box because you are not finding that type of bolt and head at ACE or NAPA. When the bolts become loose, you will get a bang from the drive train in 4wd or a vibration at high speed before it becomes obvious to the eye. So, it does not hurt to put a wrench on the bolts and check for tightness every once in a while or after an off road session.

$0.02

 

[gw33gp]

I am very familiar with what you are saying. I know it is not obvious but I have been doing this stuff since 1977. That does not make me an expert, but some things do soak into my thick head over time. Don't get me wrong, I appreciate your advice because I never know when I can learn something new.

It seems I did not make myself clear. I found out it was not the drivetrain that was banging. It was the inner tie rod that was banging due to excessive wear and play. When the drivetrain would bind while going around a corner down hill, the slip of a tire would cause the inner tie rod to bang when that energy was released. I am guessing, as you said, more weight being on the front while going down hill caused traction to be greater and more energy was released when the tire slipped causing more of a bang. With the new inner tie rods, that banging has not occurred in the past 2 and 1/2 years.

I doubt anyone checks the drivetrain on their vehicles more than I do. I do a lot of long term off-road adventures and don't want to get stranded in the wilderness. A thorough check of everything of my vehicle is step number one before I head out on a new adventure. A post inspection is normally done also since it is also my daily driver.